With just a small sample of blood, Stanford researchers have figured out a way to track the evolution of lung tumors. The technique could help clinicians monitor the genes of cancerous cells as they develop resistance to particular chemotherapies, allowing them to select a new therapy that is more likely to be effective.
Currently, monitoring lung cancer requires an invasive biopsy or a CT scan, which exposes the patient to damaging X-rays. Without information, physicians are often forced to make an educated guess about the best therapy to try next. "Blood-based monitoring would allow us to select the right second and third therapies, instead of flying blind," said Seung-min Park, PhD, a Stanford radiology instructor and a lead author of the new study.
The research appears in the Proceedings of the National Academy of Sciences. The technique identifies circulating tumor cells, or CTCs, which are tumor cells that are found in the blood stream that play a role in metastasis, or the spread of tumors from one location to another. A Stanford Medicine press release explains:
The blood typically contains very few CTCs, so one of the challenges for oncologists has been to separate them from ordinary blood cells. The new technique involves taking blood from lung cancer patients and then attaching antibodies to circulating tumor cells. Once the cancer cells are labeled, the team introduces magnetic nanoparticles designed to attach to the antibodies labeling the cancer cells. With each individual cancer cell labeled with a magnetic nanoparticle, the researchers can then use a device called a magnetic sifter, or MagSifter [shown in the photo above], previously developed by [Shan] Wang [PhD, professor of materials science and engineering and of electrical engineering].
The MagSifter is an electromagnetic sieve that can be turned on and off. When the MagSifter is on, it pulls the nanoparticle-labeled CTCs from the blood sample and allows the rest of the blood to flow through the sifter. The CTCs pulled from the blood are then deposited into a flat array of tiny wells, each large enough for only one cell. Now the tumor cells are ready for genetic analysis. Each flat of 25,600 wells looks like a miniature muffin tin, with room for a lot of tiny muffins.
If it is approved by the Food and Drug Administration, the technique could have both research and clinical applications, the researchers say.
Previously: Fighting cancer on a tiny stage, Minuscule DNA ring tricks tumors into revealing their presence and Beam me up! Detecting disease with non-invasive technology
Photo by Seung-min Park